> > > Unless the relation holds all possible values of a type,> the relation cannot be considered equivalent to the type> itself.

Well, if you want to hold to the relational orthodoxy, you ought to call
those relvar. But to make it clear we'll call them table, shall we ?

Now who said that relation should be considered to be equivalent to the
type itself ? Whatever that type might be.

Now let's further consider that the table EMPLOYEE stores all the tuples
that have the type EMPLOYEE%ROWTYPE (using SQL terms, i.e. the type of
the tuples).

I'm waiting for someone to make the case why would that be such a big deal ?

> Relations are sets and thus values, not types.

Quite nice. But according to D&D types are sets of values. Well, then a
relation is a set of value.

According to proper type theory, a type is much more, of course.

According to E/R theory, that seems to be the source of inspiration for
the powerpoint incriminated here for no reason, we talk about an Entity
Type, which is identified by a name and a set of attributes (whereas an
attribute is identified by its name, and has a type).

> The difference is pedantic only until ignoring it trips> somebody up, and this has happened.>

How it happened, where it happened, how often it happened ?

For lack of better things to do, people think that if they throw
Microsoft and a couple of relational orthodoxy together, they've got a
valid point.